A conventional wire chain connector for an anchor line for anchoring a rig is shown in FIGS. 11-13, where a sheave a is mounted on a rig (not shown). A wire in the rope groove a.sub.1 is formed in the inner surface of the peripheral groove sheave a. A chain pocket a.sub.2 is formed in the central portion of the peripheral groove in the sheave a. A connector groove a.sub.3 is formed in the outer portion of the peripheral groove of the sheave a. A socket b.sub.1 that has the form of a truncated cone is firmly fixed to one end of a wire rope b. The rope b is connected to a chain c by a bell-shaped wire chain connector d. An arc-shaped horizontal member d.sub.1 is rigidly fixed to the larger lateral end of the connector d. The socket b.sub.1 is fitted in the hollow inside of the connector d that has the form of a truncated cone, to connect the rope b with the connector d. A link c.sub.1 at one end of the chain c engages the arc-shaped horizontal member d.sub.1 of the connector d to connect the connector d with the chain c. An anchor (not shown) is attached to the other end of the chain c. The rope b is attached to a winch (not shown) on the rig at its other end. When the winch is driven to wind up or pay out the rope b, the rope b passes along the groove a.sub.1 formed in the inner surface of the peripheral groove in the sheave a. The chain c passes along the chain pocket a.sub.2 formed in the central portion of the peripheral groove of the sheave a. The wire chain connector d passes along the groove a.sub.3 formed in the outer portion of the peripheral groove of the sheave a.
Another conventional wire chain connector for an anchor line is shown in FIG. 14, where a socket b.sub.2 is firmly fixed to a wire rope b. A link b.sub.3 is integral with the socket b.sub.2. A wire chain connector d is composed of a ball adapter d.sub.2, U-shaped links d.sub.3 and d.sub.4, and a pin d.sub.5 for rotatably holding the links d.sub.3 and d.sub.4 to the adapter d.sub.2. The link b.sub.3 on the side of the rope b engages the U-shaped link d.sub.4 on the side of the connector d to connect the rope b with the connector d. The link c.sub.1 at one end of the chain c engages the U-shaped link d.sub.3 of the connector d to connect the chain c with the link d.sub.3. An anchor (not shown) is attached to the other end of the chain c. The other end of the rope is attached to the winch on the rig. When the winch is driven to wind up or pay out the rope b, the rope passes along a wire rope groove formed in the inner surface of the peripheral groove of a sheave. The chain passes along a chain pocket formed in the central portion of the peripheral groove of the sheave. The wire chain connector passes along a connector groove formed in the outer outer portion of the peripheral groove of the sheave.
The structures and the shapes of the sheave a and the wire chain connector d of the aforementioned anchor line must be so determined that when the line passes around the sheave a, no excessive force is applied to the wire rope b or the chain c; otherwise their durability would deteriorate. However, the connectors d shown in FIGS. 11-14 are unsatisfactory in this respect.
The wire chain connector d shown in FIGS. 11-13 is now discussed in more detail. When the arc-shaped horizontal member d.sub.1 is located parallel to the axis of the sheave a as shown in FIG. 11 and the connector d is fitted in the connector groove a.sub.3 in the sheave a, the resultant HvH of the tensions lies on the contact line between the bottom d' of the connector d and the groove a.sub.3. Therefore, no rotation moment, or torque, is produced on the connector d. When the horizontal member d.sub.1 is located at right angles to the axis of the sheave a as shown in FIG. 12 and the connector d is fitted in the groove a.sub.3 in the sheave a, the link c.sub.1 at one end of the chain c is moved to the left toward the center of the sheave a, because the horizontal member d.sub.1 has an arc-shaped form. The resultant H of tensions is moved upwardly away from the contact line between the bottom d' of the connector d and the groove a.sub.3. Thus, a rotation moment is generated on the connector d. As a result, a strong bending stress is produced on the wire rope b in the vicinity of the socket b.sub.1. This will impair the durability of the rope b. It is to be understood that in the above description, the connector d is fitted in the groove a.sub.3 in the sheave a while the horizontal member d.sub.1 is located perpendicularly to the axis of the sheave a, for ease of understanding. In practice, if the horizontal member is inclined at any angle to the axis of the sheave a, then a bending stress is produced on the rope b. The shape of the connector d may be changed to prevent a bending stress from occurring on the rope b near the socket b.sub.1 even if the connector d is fitted in the groove a.sub.3 in the sheave a while the horizontal member d.sub.1 lies perpendicularly to the axis of the sheave a. In this case, if the connector d is fitted in the groove a.sub.3 in the sheave a while the horizontal member d.sub.1 lies parallel to the axis of the sheave a, then a bending stress will be produced on the rope b. Also, it is difficult to change the direction of the connector d as shown in FIG. 12 to the direction shown in FIG. 11 before the connector d is fitted in the groove a.sub.3 in the sheave a, because tension is applied to it, and because the sheave a may be placed below water level. Another problem arises from the fact that the connector d is shaped in the bell-shaped form and that the link c.sub.1 of the chain c is mounted in the connector d via the horizontal member d.sub.1. More specifically, the angle through which the anchor line is wound on the sheave a is limited to about 45.degree.. The result is that it cannot pass a deck sheave or the like on which an anchor line must be wound at an angle of 90.degree. to 180.degree..
In the case of the wire chain connector d shown in FIG. 14, the U-shaped link d.sub.4 is connected to the link b.sub.3 on the side of the rope b, and the U-shaped link d.sub.3 is connected to the link c.sub.1 at one end of the chain c. Therefore, these links are bulky, which is unfavorable for the strength. Further, since the U-shaped links d.sub.3 and d.sub.4 are rotatably held to the ball adapter d.sub.2 via the pin d.sub.5, if the adapter d.sub.2 is seated in the connector groove d.sub.2 in the sheave a, the adapter d.sub.2 is prevented from rotating in the groove a.sub.3. As a result, excessive force is applied to the sheave a.